Even more so than for others, people with disabilities can find using a computer to be a challenge. For example, vision difficulties and impairments including low vision, color blindness, and blindness can make reading the screen difficult. Among adult computer users in the United States, it is estimated that more than one quarter experience some kind of vision difficulty.
Today, there are a number of options for individuals with vision difficulties to modify their computer displays and appearance to make them easier to see, or, alternatively, to receive information through sound or touch. One aspect of making it easier for people with visual and cognitive impairments to use a computer is ensuring that user interfaces adhere to certain standards of text contrast. For example, a 5:1 luminosity ratio for text against the background color is generally considered vision-friendly.